Slide-zipper assembly, method of attaching slide-zipper assembly to thermoplastic film, and method of making slide-zippered packages

CROSS REFERENCE TO RELATED APPLICATIONS. This is a division of U.S. Pat. application Ser. No. 09/361,087 filed on Jul. 26, 1999. Now Pat. No. 6,212,857.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of reclosable packaging. More particularly, the present invention relates to a slide-zipper assembly; a method of attaching the slide zipper assembly to thermoplastic film; and a method of making slide-zippered packages, preferably on a form-fill-seal (FFS) machine.

2. Description of the Prior Art

Slide-zipper assemblies are well-known in the reclosable packaging art, such as those slide-zipper assemblies disclosed in U.S. Pat. Nos. 5,007,143, 5,008,971, 5,131,121 and 5,664,299. Methods of making reclosable packages on FFS machines are likewise well-known in the reclosable packaging art, such as those methods disclosed in U.S. Pat. Nos. 4,909,017, 4,655,862 and 4,894,975.

Because of the facility which is provided by slide-zippers to consumers of reclosable packages and because of the large volume of reclosable packages made on FFS machines today, it is highly desirable and advantageous to combine the two technologies so that slide-zippered packages can be made on FFS machines.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a new type of slide-zipper assembly particularly suited for use in the manufacture of slide-zippered packages on FFS machines. Another object of the present invention is to provide a method of attaching the slider zipper assembly to thermoplastic film, which thermoplastic film can subsequently be used to make slide-zippered packages on an FFS machine or the like. Yet another object of the present invention is to provide a method of making slide-zippered packages, preferably on an FFS machine.

According to a first aspect of the present invention, a reclosable zipper is provided. The reclosable zipper is comprised of a first profile interlockable with a second profile. Each profile includes an interlocking member and a flange extending from the interlocking member on one side thereof at the bottom of the zipper. The interlocking members are interlockable with one another. The zipper flanges are wrapped around the zipper and joined together at the top of the zipper. Optionally, a slider may be included for opening and closing the zipper. The slider straddles the zipper and is adapted to open the zipper as it is moved therealong in an opening direction and to close the zipper as it is moved therealong in a closing direction.

According to a second aspect of the present invention, lengths of the reclosable zipper are attached to thermoplastic film via the connected flanges. The zipper-equipped thermoplastic film may then be fed into an FFS machine or rolled up for later use.

According to a third aspect of the present invention, the zipper-equipped thermoplastic film is fed into an FFS machine or the like where it is made into reclosable packages.

The present invention will now be described in detail, with frequent reference being made to the drawings identified below in which the same numerals represent the same elements.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. <b>1</b>(<i>a</i>) and <b>1</b>(<i>b</i>) are cross-sectional views of a length slide-zipper assembly in accordance with the present invention;

FIG. 2 is a perspective view of slide-zipper assembly lengths being attached transversely to thermoplastic film;

FIG. 3 is a perspective view of slide-zipper assembly lengths attached longitudinally to thermoplastic film;

FIG. 4 is a perspective view of slide-zippered packages being made on an FFS machine;

FIG. 5 is a front view of a package made on the FFS machine of FIG. 4;

FIGS. <b>6</b>(<i>a</i>), <b>6</b>(<i>b</i>) and <b>6</b>(<i>c</i>) are cross-sectional views of the package of FIG. 5 as it is being opened; and

FIG. 7 is a plan view of a length of slide-zipper assembly in accordance with an alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the first aspect of the present invention, a cross-sectional view of a length of slide-zipper assembly <b>10</b> is shown in FIGS. 1 (<i>a</i>) and <b>1</b> (<i>b</i>). The slide-zipper assembly <b>10</b> includes a reclosable zipper <b>12</b> and a straddling slider <b>14</b>. The slider <b>14</b> is adapted to open the zipper <b>12</b> as it is moved therealong in an opening direction and to close the zipper <b>12</b> as it is moved therealong in a closing direction. Although the slider <b>14</b> is included in the preferred embodiment, the slider <b>14</b> is optional and is not necessary to practice the present invention.

The zipper <b>12</b> includes a first profile <b>16</b> and a second profile <b>18</b>. The first profile <b>16</b> includes an interlocking member <b>20</b> and a flange <b>22</b> extending from the interlocking member <b>20</b> on one side thereof at the bottom of the slide-zipper assembly <b>10</b>. Similarly, the second profile <b>18</b> includes an interlocking member <b>24</b> and a flange <b>26</b> extending from the interlocking member <b>24</b> on one side thereof. The interlocking members <b>20</b>, <b>24</b> are interlockable with each other and are designed to cooperate with the slider <b>14</b> so that they may be readily engaged and disengaged as the slider <b>14</b> is moved along the zipper <b>12</b> in the closing and opening directions, respectively. The interlocking members <b>20</b>, <b>24</b> may have any shape which permits their releasable engagement.

Preferably, the zipper flanges <b>22</b>, <b>26</b> are coextruded with their corresponding interlocking members <b>20</b>, <b>24</b>, but may be extruded separately and attached later, such as by welding or by an adhesive. The zipper <b>12</b> and slider <b>14</b> are each made of a resilient plastic.

As shown in FIG. 1 (<i>b</i>), the zipper flanges <b>22</b>, <b>26</b> are of a sufficient length that they can be wrapped around the interlocking members <b>20</b>, <b>24</b> and the slider <b>14</b> and connected together at a connection point <b>28</b> at the top of the zipper. The flanges <b>22</b>, <b>26</b> may be welded together or connected through use of an adhesive at the connection point <b>28</b>. Additionally, a perforation <b>30</b> is provided on each flange between the connection point <b>28</b> and the interlocking members <b>20</b>, <b>24</b>. These perforations facilitate the use of the slide-zipper assembly <b>10</b> in reclosable packages, as discussed in detail below.

In accordance with the second aspect of the present invention, lengths of slide-zipper assembly <b>10</b> are attached to thermoplastic film <b>34</b> which may be used to make reclosable packages on an FFS machine. The slide-zipper assembly lengths <b>10</b> may be attached to the thermoplastic film <b>34</b> transversely to the running direction, as shown in FIG. 2, or parallel to the running direction, as shown in FIG. <b>3</b>. The former method is commonly known as the “transverse zipper” method, while the latter method is commonly known as the “longitudinal zipper” method.

With respect to the transverse zipper method illustrated in FIG. 2, the slide-zipper assembly lengths <b>10</b> are attached to the thermoplastic film <b>34</b> via the ends <b>32</b> of the connected flanges <b>22</b>, <b>26</b>. The slide-zipper assembly lengths <b>10</b> may either be pre-cut to the required length or, as shown in FIG. 2, may be supplied from a supply roll <b>36</b>.

As shown in FIG. 2, the slide-zipper assembly <b>10</b> is pulled across the thermoplastic film <b>34</b> by a positioning device <b>38</b>, which positions the slide-zipper assembly lengths <b>10</b> on the thermoplastic film <b>34</b> and cuts them from the continuous roll <b>36</b>. The positioning device <b>38</b> can take any of a variety of forms well-known to those skilled in the reclosable packaging art, such as a vacuum conveyor for pulling the slide-zipper assembly across the thermoplastic film <b>34</b> and a knife for cutting the slide-zipper assembly lengths <b>10</b> from the continuous roll thereof <b>36</b>.

The thermoplastic film <b>34</b> is paid off a continuous roll <b>40</b> in increments equal to the length of the packages which will ultimately be formed from the film <b>34</b> in an FFS machine. Each time the film <b>34</b> comes to rest locally, a slide-zipper assembly length <b>10</b> is disposed on the thermoplastic film <b>34</b> transverse to the running direction with the ends <b>32</b> of the connected zipper flanges <b>22</b>, <b>26</b> projecting in the running direction and with one of the interlocking members above the other relative to the thermoplastic film <b>34</b>. The flanges so oriented allow the slide-zipper assembly <b>10</b> to pass freely over the forming collar of an FFS machine. As disclosed in U.S. Pat. No. 4,909,017, the slide-zipper assembly lengths <b>10</b> have a length approximately equal to half the width of the film <b>34</b> and are disposed centrally thereon. However, the slide-zipper assembly lengths <b>10</b> may also be positioned at different locations on the film, such as adjacent an edge of the film. Seal bars <b>42</b> are positioned to seal the zipper flanges to the thermoplastic film <b>34</b> between the perforations <b>30</b> and the connection point <b>28</b>. The seal, which is denoted by a series of x's, may be a tack seal or a full seal.

For proper functioning, the zipper interlocking members <b>20</b>, <b>24</b> should be spot sealed together at the ends of the slide-zipper assembly lengths <b>10</b>. This ensures that the zipper halves will not come apart during use and also provides end stops for the slider <b>14</b>. If the slide-zipper assembly lengths <b>10</b> are pre-cut, this sealing can take place during the cutting process, or even earlier. If the lengths are supplied from a continuous roll, then the positioning device can be adapted to make these spot seals. However, only the interlocking members <b>20</b>, <b>24</b> should be spot sealed together. The zipper flanges <b>22</b>, <b>26</b> should not be sealed together at the ends of the slide-zipper length <b>10</b>. This will allow the slide-zipper to be extended from the package when the package is opened for the first time.

Once the slide-zipper assembly lengths <b>10</b> are attached to the thermoplastic film <b>34</b>, the film may be rolled up for later use, or may be fed into an FFS machine or the like and formed into packages.

Alternatively, as shown in FIG. 3, the slide-zipper assembly lengths <b>10</b> may be attached to the film along an edge thereof parallel to the running direction, the so-called longitudinal zipper method. In that case the ends <b>32</b> of the zipper flanges <b>22</b>, <b>26</b> are attached to the thermoplastic film <b>34</b> adjacent an edge. As with the transverse zipper method, the slide-zipper assembly lengths <b>10</b> may be pre-cut or supplied from a continuous roll. In the latter case, the supply roll <b>36</b> and positioning device <b>38</b> shown in FIG. 2 are positioned inline with the thermoplastic film <b>34</b>.

In the third aspect of the present invention, the thermoplastic film <b>34</b> with slide-zipper assembly lengths <b>10</b> attached thereto is fed into an FFS machine <b>44</b> or the like. Methods of making reclosable packages on FFS machines using transverse and longitudinal zippers are well-known and are disclosed in U.S. Pat. Nos. 4,909,017, 4,655,862 and 4,894,975, the disclosures of which are incorporated herein by reference.

FIG. 4 shows an FFS machine <b>44</b> configured to make transverse slide-zippered packages. As shown in FIG. 4, the thermoplastic film <b>34</b> is fed downwardly over the collar <b>46</b> and folded around filling tube <b>48</b>. The edges of the film are brought together and pressed together by a pair of rollers <b>50</b>. The edges are then welded together by a pair of longitudinal seal bars <b>52</b> to form a longitudinal back seal <b>54</b>. Contents may then dropped through the tube <b>48</b> into the package which is presently being formed <b>56</b>, which has a lower seal <b>58</b> which was formed when the immediately preceding package <b>60</b> was completed.

After introduction of the contents, the top (which will actually be the bottom of the package during use) of the instant package <b>56</b> and the bottom (which will actually be the top of the package during use) of the succeeding package <b>61</b> are completed by the action of the cross seal jaws <b>62</b>, which perform six simultaneous or nearly simultaneous functions.

With respect to the bottom of the succeeding bag <b>61</b>, the cross seal jaws <b>62</b> seal the portions of the zipper flanges <b>22</b>, <b>26</b> between the perforations <b>30</b> and the interlocking members <b>20</b>, <b>24</b> to the front and back walls <b>64</b>, <b>66</b> of the bag <b>61</b> without sealing the flanges to each other. The flanges may be coated with a heat activated adhesive to prevent the flanges from sealing to each other. Second, the cross seal jaws <b>62</b> seal the bottom of the bag <b>61</b> to form a pilfer evident lower seal <b>58</b>. The connected zipper flanges <b>22</b>, <b>26</b> extend into the pilfer evident seal. Third, the sides <b>70</b>, <b>72</b> of the package <b>61</b> are spot sealed <b>71</b> and notched <b>73</b> in-line with the perforations <b>30</b> on the zipper flanges <b>22</b>, <b>26</b>. The longitudinal back seal may also be notched in-line with the perforations <b>30</b> as well.

With respect to the instant bag <b>56</b>, the cross seal jaws <b>62</b> then make the top seal <b>68</b> and cut the bag <b>56</b> from the thermoplastic film <b>34</b>. As shown in FIG. 4, the completed package <b>60</b> has a top seal <b>68</b>, a transverse slide-zipper assembly length <b>10</b>, a pilfer evident lower seal <b>58</b>, a longitudinal back seal <b>54</b> and two spot seals <b>71</b> and three notches <b>73</b> in -line with the perforations <b>30</b> on the zipper flanges <b>22</b>, <b>26</b>.

When the completed package <b>60</b> is used by the consumer, it is inverted so that the slide-zipper assembly <b>10</b> is at the top of the package <b>60</b>, as shown in FIG. <b>5</b>. To initially open the sealed package, the user tears off the top of the package, using one of the side notches <b>73</b> to start the tear. Because the spot seals <b>71</b> and notches <b>73</b> are in-line with the zipper perforations and because the connected zipper flanges <b>22</b>, <b>26</b> extend into the pilfer evident top seal <b>58</b>, the portions <b>75</b> of the zipper flanges <b>22</b>, <b>26</b> between the perforations <b>30</b> and the connection point <b>28</b> are tom off as well. To gain access to the interior of the package, the user extracts the slide-zipper assembly <b>10</b> up and out of the package. The user then simply moves the slider <b>14</b> along the zipper <b>12</b> in the opening direction to gain access to the interior of the package <b>60</b>. If a slider is not present, it is unnecessary to extract the zipper <b>10</b> out of the package. This accessing and opening process is illustrated in FIGS. <b>6</b>(<i>a</i>)-<b>6</b>(<i>c</i>).

In the case where a longitudinal zipper is used, the FFS machine of FIG. 4 is configured so that the longitudinal seal bars <b>52</b>, and not the cross-seal jaws <b>62</b>, seal the zipper flanges <b>22</b>, <b>26</b> to the package walls and create the pilfer evident seal <b>58</b> and side notches <b>73</b> and spot seals <b>71</b>. Additionally, the cross-seal jaws are rotated 90° in order to complete the package side seals. Accessing and opening of the completed package is accomplished in the same manner as discussed above.

To enhance extraction of the slide-zipper assembly from the completed package, the zipper flanges <b>22</b>, <b>26</b> may be tapered and sealed together at the ends of the slide-zipper lengths <b>10</b>, as shown in FIG. <b>7</b>. These tapered seals <b>76</b> will make it easier for the user to pull the slide-zipper assembly from the inside of the package. These tapered seals can be made at the same time the interlocking members are spot sealed <b>78</b> together, either by the positioning device <b>38</b> or earlier if the slide-zipper assembly lengths <b>10</b> were pre-cut.

Thus, in the foregoing manner the object of the present invention is achieved. Modifications to the above would be obvious to those of ordinary skill in the art, but would not bring the invention so modified beyond the scope of the appended claims.